466 Imperial Institute of France, 



body divided into two lobes ; at two-thirds of its height 

 and between these lobes, there is a small membranous sac, 

 from which proceed the first leaves, and it is only after the 

 stalk which bears these leaves is a little lengthened, that it 

 produces laterally some small roots. 



Messrs. Mirbel and Poiteau, in conformity to a resem- 

 blance at least apparent, have asserted that the two lobes 

 are the two cotyledons ; that the first leaves form the plu- 

 mule, and the sac which envelops them is a kind of 

 sheath: that the radicle remains inactive and without de- 

 velopment, and that the fibres which arise from the small 

 stalk are analogous to those roots which iisue from rampant 

 plants. 



M. de Mirbel, in particular, thinks that he has found in 

 the interior of these lobes, a set of vessels entirely similar 

 to those of the cotyledons in the plants which have double 

 cotyledons. These two botanists have therefore ranged the 

 nelumbo among the dicotylcdones. 



M. Richard, on the contrary, maintains that it is the 

 small sac which ought to be considered as the only cotyle- 

 don, and that the two lobes belong to the extremity of the 

 radicle : he compares these bodies with those observed in 

 other embryos, and to which he has given the name of 

 hypoblasli, being the same which Gaertner called vitellus ; 

 and this analogy appeared to him to be the clearer, because 

 the lobes in question, as well as the other hypoblasti, exhi- 

 bit no growth at the time of germination, and the contrary 

 is the case with most of the cotyledons. The lateral pro- 

 duction of the 'roots is a natural and general consequence 

 of the presence of a hypoblaslus, which hinders the radicle 

 .from shooting out in a straight line. According to this 

 reasoning, M. Richard has classed the nelumbo among the 

 mono-cotyledones. 



The discussion afterwards turned upon the nature of these 

 hypoblasti. M. de Mirbel has compared what M. Richard 

 calls by this name among the grasses, and which is the scu- 

 tellum of Gaenner, with the cotyledon of the asparagus and 

 some other plants which have only one, and has concluded 

 from the comparison, that the hypoblastus of the grasses is 

 precisely their cotyledon : this would give him the advan- 

 4age of all the analogies cited by M. Richard. 



M. Poiteau has also given in a memoir upon this question, 

 taking the same side with M. Mirbel. 



M. Richard, in reply, maintains that there is a greater 

 difference than M. Mirbel is aware of; that the plumula of 

 the asparagus and of the other plants mentioned, is enve- 

 loped 



